(Applicant's Abstract) The Clinical Core serves as the resource for clinical samples and data related to both clinical and basic studies of the pathogenesis and treatment of BPD. As the link between infants in the neonatal intensive care units and laboratories of the SCOR, the Clinical Core is the comer stone of the translational component of the SCOR program. Two groups of premature infants will be entered into protocols under the coordination of the Clinical Core. First, in an ongoing study, all premature infants equal to or less than 32 weeks gestation who require intubation in the first day of life (Group A) are enrolled in a prospective study of biochemical markers potentially related to development of BPD. Extensive clinical data are collected on the clinical course and outcome of the infants and these are entered into an established data base maintained by the Department of Biostatistics. Samples of tracheal aspirate, blood and urine are collected at designated intervals over the first 28 days of life and made available to SCOR investigators for studies of surfactant proteins, selected cytokines growth factors, and hyaluronic acid. Analyses of these results provide information on the postnatal pattern of expression and association with morbidities of the preterm newborn including BPD. In addition, specimens of lung tissue are obtained in cases of lung biopsy or postmortem and provided to SCOR investigators. In a second clinical protocol (Group B), clinical samples and data are collected on premature infants enrolled in a multicenter clinical trial of inhaled Nitric Oxide (iNO) to prevent BPD (the NO CLD study). This trial was initiated in April 2000 with NIH funding (R. Ballard, PI) and will enroll 726 infants over three years. Enrollment will be completed by March, 2004 and analysis of response by treatment group will then occur. Clinical samples will be collected before initiation of nitric oxide (or placebo nitrogen) therapy, at intervals during treatment, and after discontinuing therapy. Studies by SCOR investigators, particularly Projects 1, 6 and 4 will assess effects of iNO related to issues of efficacy, safety and mechanism of action. A future initiative of the SCOR will be to obtain white blood cells from infants for establishment of cell lines that will serve as a source of DNA for collaborative studies of candidate genes related to susceptibility for development of BPD as well as response to iNO. The large database on premature infants developed by the Clinical Core constitutes a valuable and unique resource for generation of new hypotheses regarding the pathogenesis of BPD as well as rigorous testing of current working models.